Auxiliary power supply system for high power loads in a vehicle

ABSTRACT

An apparatus includes a first interface, a first converter, a high-voltage battery, a second converter and a second interface. The first interface may be configured to receive a first low-voltage signal from first power rail of a vehicle. The first converter may be configured to generate a high-voltage signal by up-converting the first low-voltage signal. The high-voltage battery may be configured to store the high-voltage signal. The second converter may be configured to generate a second low-voltage signal by down-converting the high-voltage signal. The second interface may be configured to present the second low-voltage signal to a second power rail of the vehicle. The first power rail may be electrically separated from the second power rail.

This application relates to Italian Application No. 102018000006784,filed Jun. 28, 2018, which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The invention relates to vehicle power systems generally and, moreparticularly, to a method and/or apparatus for implementing an auxiliarypower supply system for high power loads in a vehicle.

BACKGROUND

Improvements in electronics for modern automobiles result in highcurrent demands. While an internal combustion engine of the automobileis running, a generator can create a limited amount of current. Theamount of current is determined by the manufacturer to meet a maximumcurrent that the automobile systems can consume. A small “extra” currentcapacity is commonly left in reserve. After-market high-power loadsadded to the automobile typically exceed the reserve current capacity ofthe generator. Furthermore, when the internal combustion engine isswitched off, conventional batteries typically cannot meet thesteady-state current demands of the high-power loads. If the batteriescan satisfy the loads, the batteries are usually drained in a shorttime.

It would be desirable to implement an auxiliary power supply system forhigh power loads in a vehicle.

SUMMARY

The invention concerns an apparatus including a first interface, a firstconverter, a high-voltage battery, a second converter and a secondinterface. The first interface may be configured to receive a firstlow-voltage signal from first power rail of a vehicle. The firstconverter may be configured to generate a high-voltage signal byup-converting the first low-voltage signal. The high-voltage battery maybe configured to store the high-voltage signal. The second converter maybe configured to generate a second low-voltage signal by down-convertingthe high-voltage signal. The second interface may be configured topresent the second low-voltage signal to a second power rail of thevehicle. The first power rail may be electrically separated from thesecond power rail.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the invention will be apparent from the followingdetailed description and the appended claims and drawings in which:

FIG. 1 is a diagram of a vehicle in accordance with an embodiment of theinvention;

FIG. 2 is a diagram of an electrical system of the vehicle accordancewith an embodiment of the invention; and

FIG. 3 is a state transition diagram of an electronic control unit ofthe electrical system in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention include providing an auxiliarypower supply system for high power loads in a vehicle that may (i)provide an after-market technique to accommodate high-power electricalloads, (ii) provide current beyond a main power distribution systemcapacity, (iii) power electrical loads for a long time while an engineis switched off, (iv) operate from electrical power received from a wallsource (v) operate from electrical power received from an auxiliarysource and/or (vi) provide uninterrupted electrical power whilehot-swapping between power sources.

Embodiments of the invention generally provided an auxiliary powersystem and auxiliary power distribution technique that are capable ofpowering a secondary power bus independent from a main electrical bus ofan internal combustion engine type vehicle (e.g., automobile, truck,bus, etc.). A generator (or alternator) of the vehicle may generateelectrical power derived from the internal combustion engine. Use ofelectrical power from the generator may be considered a “vehicle poweredmode.” The generated electrical power may be shared by the auxiliarypower system and a main (or normal) power system. The secondary powerbus and the main power bus may be electrically independent of eachother, except for the common connection to the generator. The secondarypower bus may be operational while the internal combustion engine of thevehicle is switched off and thus the main power bus is dependent on avehicle (or normal) battery.

Various embodiments of the invention may utilize the auxiliary powersystem to provide electrical power to high power loads connected to thesecondary power bus. In some cases, the high power loads may be loadsthat draw on average more electrical current than the main power bus candistribute. In various situations, the high power loads may be loads thedraw surge currents greater than a capacity of the vehicle generator andthe vehicle battery without impacting the rest of the vehicleelectronics. In some embodiments, the auxiliary power system may provideup to 15 kilowatts (kW) of power to the secondary power bus for extendedperiods. For example, the auxiliary power system may provide 1.5 kW ofpower to loads on the secondary power bus from a 10 kW hour (kWh)capacity battery for up to 6.4 hours, 5 kW of power from a 30 kWhcapacity for 6 hours, and 15 kW of power from a 100 kWh capacity for upto 6.4 hours after the vehicle engine is switched off and an internalhigh-voltage battery is fully charged.

In various embodiments, the auxiliary power system may receiveelectrical power from an AC powered battery charger connection and/oranother source (e.g., an auxiliary power unit) inside and/or outside thevehicle. Distribution of electrical power from the battery charger maybe referred to as a “wall powered mode.” Distribution of electricalpower from the auxiliary power unit may be referred to as an “auxiliarypower mode.” The battery charger may drive the high power loads for anunlimited amount of time during indoor employment or outdoor employment(e.g., software testing, etc.) with the vehicle engine off. Theunlimited engine-off operation of the high power loads may allowsufficient time to perform diagnostics, uploading and/or downloading ofinformation to and from the electronics. For example, data gathered andstored during autonomous-driving trips may be downloaded from autonomousdriving computers powered through the secondary power bus while thevehicle is inside a garage. Electrical power from the battery chargerand/or auxiliary power unit may also be used to charge one or morebatteries internal to the auxiliary power system.

The auxiliary power system may provide electrical power to the secondarypower bus in the absence of power from the vehicle generator, thebattery charger and the auxiliary power unit. The auxiliary power systemmay also enable hot swapping among the various sources of electricalpower. A backup battery internal to the auxiliary power system generallyallows smooth switching among the vehicle power mode, the wall powermode and the auxiliary power mode without interrupting or compromisingoperations of the loads that rely on power from the secondary power bus.

Referring to FIG. 1, a diagram of an example implementation of a vehicle70 is shown in accordance with an embodiment of the invention. Thevehicle 70 may be an automobile, a truck, a bus, or any other passengerand/or cargo carrying vehicle powered by an internal combustion engine.The vehicle 70 may include an engine compartment (or area), a passengercompartment (or area) and a trunk compartment (or area) The vehicle 70generally comprises an engine 72, a device (or circuit) 82, a device (orcircuit) 84, a device (or circuit) 86, a device (or circuit) 88, adevice (or circuit) 90, a device (or circuit) 92, a device (or circuit)94 and a device (or circuit) 100.

A signal (e.g., CSA) may be transferred between the device 92 and thedevice 100. The signal CSA may carry command data and status databetween the devices 92 and 100. A signal (e.g., LVA) may be generated bythe device 82 and transferred by the device 88 to the devices 84, 86 and100. The signal LVA may implement a low-voltage power signal. A signal(e.g., LVB) may be generated by the device 100 and transferred to thedevice 94 via the device 90. The signal LVB may implement anotherlow-voltage power signal.

The engine 72 may implement an internal combustion engine. The engine 72is generally operational to provide mechanical power to a transmissionof the vehicle 70 and the device 82.

The device 82 may implement a vehicle generator. The vehicle generator(or alternator) 82 is generally operational covert mechanical power froman engine of the vehicle 70 into low-voltage electrical power as thesignal LVA. In various embodiments, the low-voltage generated by thevehicle generator 82 may range from approximately 10 volts DC toapproximately 50 volts DC (VDC) (e.g., 12 VDC, 24 VDC and/or 48 VDCelectrical systems). The vehicle generator 82 is generally located inthe engine compartment.

The device 84 may implement a battery. In various embodiments, thebattery 84 may be a normal automotive (or vehicle) battery. The vehiclebattery 84 may be charged by the vehicle generator 82 via the signalLVA. The vehicle battery 84 may provide electrical power in the signalLVA to other electronics in the vehicle 70 while being discharged. Thelow-voltage generated by the vehicle battery 84 may range fromapproximately 8 volts DC to approximately 50 volts DC. The vehiclebattery 84 is generally located in the engine compartment.

The device 86 may implement vehicle service load devices (or circuits).The service load devices (or service loads for short) 86 may receiveelectrical power from the vehicle generator 82 and/or the vehiclebattery 84 in the signal LVA. The vehicle service loads 86 may include,but are not limited to, exterior lighting, interior lighting, electroniccontrol units, door locks, window motors, wiper blades, fans, radio, airconditioning, seat heaters, seat adjustments and the like. The vehicleservice loads may be located throughout the vehicle 70, in the enginecompartment, the passenger compartment, the trunk and/or otherlocations.

The device 88 may implement a main low-voltage bus (or power rail). Themain low-voltage bus 88 may be operational to distribute the signal LVAamong the vehicle generator 82, the vehicle battery 84, the vehicleservice loads 86 and the device 100. In various embodiments, the mainlow-voltage bus 88 may utilize the vehicle chassis as a ground bus.

The device 90 may implement an auxiliary low-voltage bus (or powerrail). The auxiliary low-voltage bus 90 may be operational to distributethe signal LVB from the device 100 to the device 94. The auxiliarylow-voltage bus 90 may be electrically isolated from the mainlow-voltage bus 88. The isolation may include separate hot wires andseparate ground wires from the main low-voltage bus 88. In variousembodiments, the low voltage generated by the device 100 in the signalLVB may range from approximately 10 volts DC to approximately 50 voltsDC.

The device 92 may implement a user interface device (or circuit). Theuser interface device 92 may be operational for bidirectionalcommunication with the device 100 via the signal CSA. The communicationsmay be based on an Ethernet protocol, a Controller Area Networkprotocol, a Universal Serial Bus protocol or similar standardtechniques. Information conveyed by the signal CSA may include, but isnot limited to systems status, current energy source status, flowingcurrent, voltages and estimated remaining time using the battery at thecurrent rate. The user interface device 92 may allow a user to switchbetween different energy sources and/or different system statusindicators. The user interface device 92 is generally located in thepassenger compartment.

The device 94 may implement one or more high-power on-vehicle loaddevices (or circuits). The high-power load device (or high-power loadsfor short) 94 may receive electrical power from the device 100 in thesignal LVB. The high-power loads 94 may include, but are not limited to,cooling system, autonomous driving computers, advanced drivingassistance systems, multimedia systems, actuators and cleaning systemsfor sensors. The high-power loads may be located in multiple locationsabout the vehicle 70 including, but not limited to, a roof space, atrunk, external parts of the shell (or body), a passenger cabin and thelike.

The device 100 may implement an auxiliary power system. The auxiliarypower system (or circuit) 100 may be operational to provide low-voltageelectrical power in the signal LVB to the high-power loads 94. Theauxiliary power system 100 may also be operational to store electricalenergy in one or more internal batteries to provide a high storagecapacity in a small physical area and/or to provide for uninterruptedpower to the high-power loads during mode switches. The auxiliary powersystem 100 is generally located in the trunk and may be accessible to auser while the trunk door is open. Some parts, such as DC/DC converters,may utilize liquid cooling and so may be installed in the engine bay andlinked to the engine or other cooling system.

Referring to FIG. 2, a diagram of an example implementation of anelectrical system 80 of the vehicle 70 is shown in accordance with anembodiment of the invention. The electrical system 80 generallycomprises the vehicle generator 82, the vehicle battery 84, the vehicleservice loads 86, the main low-voltage bus 88, the auxiliary low-voltagebus 90, the user interface device 92, the high-power loads 94 and theauxiliary power system 100.

The auxiliary power system 100 generally comprises a device (or circuit)102, a device (or circuit) 104, a device (or circuit) 106, a device (orcircuit) 110, a device (or circuit) 112 and a block (or circuit) 114.The main low-voltage bus 88 may connect to the auxiliary power system100 at an interface (or port) 120. The auxiliary low-voltage bus 90 mayconnect to the auxiliary power system 100 at an interface (or port) 122.An interface (or port) 124 may connect the auxiliary power system 100 toanother low-voltage power source. The auxiliary power system 100 mayinclude an interface (or port) 126 connected to the user interfacedevice 92.

The signal LVA may be received at the interface 120 of the auxiliarypower system 100. The signal LVB may be presented from the device 108 tothe device 112 and the interface 122 of the auxiliary power system 100.A signal (e.g., LVC) may be exchanged between the device 106 and thedevice 108. The signal LVC may be a low-voltage signal. A voltagecarried by the signal LVC may be similar to the voltage in the signalLVB. A signal (e.g., LVD) may be transferred from the device 110 to thedevice 108. The signal LVD may be a low-voltage signal. A voltagecarried by the signal LVD may be similar to the voltage in the signalLVB. A signal (e.g., LVE) may be received by the device 108 from asource external to the auxiliary power system 100. The signal LVE may bea low-voltage signal. A voltage carried by the signal LVE may be similarto the voltage in the signal LVB.

A signal (e.g., HVA) may be generated by the device 102 and received bythe device 104. The signal HVA may implement a high-voltage signal. Invarious embodiments, the voltage of the signal HVA may range fromapproximately 200 volts direct current (VDC) to approximately 600 VDC. Asignal (e.g., HVB) may be exchanged between the device 104 and thedevice 108. The signal HVB may implement a high-voltage signal. Thesignal HVB may have a similar voltage range as the signal HVA. Invarious embodiments, the signals HVA and HVB may be the same signal.

The signal CSA may be exchanged between the user interface device 92 andthe device 114 through the interface 126. A signal (e.g., CSB) may beexchanged between the device 108 and the device 114. The signal CSB mayconvey commands and data between the devices 108 and 114. A signal(e.g., CMD) may be exchanged between the devices 102 and the device 114,and between the device 106 and the device 114. The signal CMD may carrycommands and data among the devices 102, 106 and 114.

The device 102 may implement a DC/DC step-up converter (orup-converter). The up-converter 102 is generally operational to generatethe high-voltage signal HVA by up-converting the low-voltage signal LVA.In various embodiments, the up-converter 102 may have a capacity topresent up to 15,000 watts of power in the signal HVA. The up-converter102 may receive control commands from the device 114 via the signal CMD.Status and data may be reported from the up-converter 102 to the device114 in the signal CMD.

The device 104 may implement a high-voltage battery. The high-voltagebattery 104 may be designed as one or more batteries (or battery packs).The high-voltage battery 104 may be one or more common hybrid/electricbatteries or one or more low-voltage batteries. Bigger vehicles mayaccommodate higher capacity batteries and/or more than one battery. Invarious embodiments, the high-voltage battery 104 may store up to 100kWh of energy. The high-voltage battery 104 may be changed from thesignal HVA and/or the signal HVB. The high-voltage battery 104 generallydischarges through the signal HVB.

The device 106 may implement a DC/DC converter. In various embodiments,the converter 106 may implement a down-converter circuit. As adown-converter, the converter 106 may generate the low-voltage signalLVC by down-converting the high-voltage signal HVB. In some embodiments,converter 106 may implement a bidirectional converter. Control betweendown-converting and up-converting may be based on commands received inthe signal CMD. As a down-converter, the bidirectional converter 106 maygenerate the low-voltage signal LVC by down-converting the high-voltagesignal HVB. As an up-converter, the bidirectional converter 106 maygenerate the high-voltage signal HVB by up-converting the low-voltagesignal LVC. In various embodiments, the converter 106 may down-convertup to 15,000 watts of power. The converter 106 may also up convert up to15,000 watts of power.

The device 108 may implement a power switch (or switch for short). Theswitch 108 may be operational to control connecting and disconnectingthe various low-voltage signals LVB, LVC, LVD and/or LVE using manualcontrol and/or electrical control. Where manual control is implemented,the switch 108 may include a manual knob (or lever) accessible from anexterior of a housing of the auxiliary power system 100. The auxiliarypower system 100 may be positioned in the trunk of the vehicle 70 suchthat the manual knob of the switch 108 is readily accessible to a user.Where electrical control is implemented, the switch 108 may communicatewith the device 114 via the signal CSB.

In various embodiments, the switch 108 may be a double-pole N-throwswitch. The value of N may range from 2 to 4, depending on the number ofpower sources available to the auxiliary power system 100. The switch108 may be operational to route low-voltage power among the signals LVB,LVC, LVD and the LVE. In various embodiments, the switch 108 may beimplemented as a break-before-make type of switch. In other embodiments,the switch 108 may be implemented as a make-before-break type of switch.In an example configuration, the switch 108 may connect and disconnectthe signals LVB and LVC (e.g., 2P1T). In another example configuration,the switch 108 may route the signal LVB between the signals LVC and LVD(e.g., 2P2T). In still another configuration, the switch 108 may switchthe signal LVB between the signals LVC, LVD and LVE (e.g., 2P3T). Theswitch 108 may also be configured to connect the signal LVD to thesignal LVC to charge the high-voltage battery 104 through the device110. The switch 108 may also be configured to connect the signal LVD tothe signals LVB and LVC simultaneously to change both the high-voltagebattery 104 and the device 112 through the device 110.

The device 110 may implement a battery charger plug (or wall plug). Thebattery charger plug 110 may be operational to generate the signal LVDfrom a power source external to the vehicle 70. In various embodiments,the power source may be a 120-volt alternating current (VAC) todirection current (VDC) power converter. Other power sources may beimplemented to meet the design criteria of a particular application.

The device 112 may implement another low-voltage battery. Thelow-voltage battery 112 may be referred to as an auxiliary system backupbattery. The auxiliary system backup battery 112 may be operational tostore up to 100 ampere hours with a high in-rush current. The auxiliarysystem backup battery 112 generally allows a smooth switching betweenthe vehicle mode and the wall power mode with the system on, withoutinterrupting or compromising an ability to deliver power to thehigh-power loads 94. In various embodiments, the auxiliary system backupbattery 112 may be located inside a housing of the auxiliary powersystem 100.

The device 114 may implement an electronic control unit (ECU). Theelectronic control unit 114 is generally operational to control theswitch 108, the converter 106 and the up-converter 102 in response tocommands received from the user interface device 92. In some designs,the electronic control unit 114 may be aware of a running/not runningstatus of the internal combustion engine 72.

During normal engine-on operations, the up-converter 102 steps up thelow-voltage power in the signal LVA generated by the vehicle generator82 to create the signal HVA. Up-converting to the higher voltage mayreduce a current value flowing in the signal HVA relative to the signalLVA. The high-voltage battery 104 may store the high-voltage power forthe auxiliary system 100. The converter 106 may be connected to thehigh-voltage battery 104 via the signal HVB. The converter 106 maygenerate the low-voltage power in the signal LVC for use internal to theauxiliary power system 100 and by the high-power loads 94. The signalLVC may also be routed to the auxiliary system backup battery 112through the switch 108.

Since the high-power loads 94 may draw power through the auxiliary powersystem 100, the total amount of power drawn may exceed the capacity ofthe vehicle generator 82 for a limited amount of time. The vehiclegenerator 82 may provide any excess power not consumed by the normalvehicle service loads 86 to the auxiliary power system 100 to charge thehigh-voltage battery 104 through the up-converter 102. With the vehiclegenerator 82 operating at or near fully capacity, the auxiliary powersystem 100 may route some of the low-voltage power received in thesignal LVA to the signal LVB. Any excess power demand may be provided tothe high-power loads 94 from the high-voltage battery 104 and theconverter 106.

The signal LVD provided by the battery charger plug 110 may also berouted to the auxiliary system backup battery 112 through the switch108. The signal LVD may be derived from an external DC power supply usedfor indoor testing, software updating, data downloads and/or batterycharging. The signal LVE may also be provided to the switch 108 throughthe auxiliary connector 124. The auxiliary connector 124 may receivelow-voltage power from another power source, such as a solar panel on aroof of the vehicle 70, or any other low-voltage power source available.

The converter 106 may be commanded to work in reverse mode andup-convert the low-voltage power in the signal LVC into the high-voltagepower in the signal HVB. Operating the converter 106 as an up-convertermay allow a recharge of the high-voltage battery 104 using power takenfrom the battery charger plug 110 or from the auxiliary connector 124. Auser may send commands and/or check DC/DC converter status using controland status signals in the signal CMD. The user can also manually and/orremotely control the switch 108 and check status of the switch 108 viathe signal CSB.

Installation of the auxiliary power system 100 in the vehicle 70 mayresolve issues with limited power available from the vehicle generator82. The vehicle generator 82 is generally designed for a maximum powerdemand and a small percentage of extra available power sized for safety.The auxiliary power system 100 may convert the unused capacity from thevehicle generator 82 and store the energy in the high-voltage battery104 and/or the auxiliary system backup battery 112. The low-voltagepower pulled from the vehicle generator 82 may be current limited toavoid damaging the vehicle generator 82. The electronic control unit 114may know the maximum amount of current of the vehicle generator 82 andthe instantaneous amount of current used by the vehicle service loads86. The electronic control unit 114 may dynamically control theup-converter 102 to adjust the amount of output current provided in thesignal HVA. By limiting the power presented in the signal HVA, theup-converter 102 may limit the input current drawn in the signal LVA.

The auxiliary power system 100 may up-convert the voltage and store thehigh-voltage power for efficiency reasons. Energy packed inhigher-voltage batteries generally occupies less volume than usinglow-voltage batteries. A ratio of energy/volume may also be higher forthe higher-voltage batteries. Therefore, high-voltage batteries maystore more energy than low voltage batteries in the same volume.Moreover, working at high voltages generally means that the flowingcurrent values are lower causing less ohmic loss in the wires.

The auxiliary power system 100 generally takes the stored high-voltagepower from the high-voltage battery pack 104 as the high-power loads 94demand. The high-voltage power may be restored to the low-voltage usingthe converter 106. The low-voltage power in the signal LVB on theauxiliary low-voltage bus 90 may physically and electrically separatefrom the main low-voltage bus 88. Keeping the two power systems separatefrom each other generally avoids malfunctions of the original equipmentmanufacturer systems caused by issues on the auxiliary loads. Forexample, a failure of one or more high-power loads 94 may corrupt theauxiliary low-voltage bus 90 but the vehicle 70 may still be started andmoved using the main low-voltage bus 88.

Referring to FIG. 3, a state transition diagram 140 of an exampleimplementation of the electronic control unit 114 is shown in accordancewith an embodiment of the invention. The state transition diagram 140generally provides multiple (e.g., five) states, including a state (ormode) 142, a state (or mode) 144, a state (or mode) 146, a state (ormode) 148 and a state (or mode) 150. The states 142 to 150 may beconsidered the states of the electronic control unit 114, the states ofthe electrical system 80 and/or the states of the vehicle 70.

The state 142 may implement a vehicle powered mode. While in the state142, if the engine 72 of the vehicle 70 is generating mechanical power,the vehicle generator 82 may convert the mechanical power into thelow-voltage signal LVA. The auxiliary power system 100 may up-convertthe low-voltage power, store the high-voltage power in the high-voltagebattery 104, and down-covert the high-voltage power back intolow-voltage power in the signal LVC. The switch 108 may by commanded toroute the signal LVC to the signal LVB to power the high-power loads 94and charge the auxiliary system backup battery 112.

The state 144 may implement a wall powered mode. When the engine 72 isstopped (e.g., ICE OFF), the electronic control unit 114 may transitionto the state 144. While in the state 144, electronic control unit 114may command the switch 108 to connect the signal LVD to the signal LVB.If low-voltage power is available from the battery charger plug 110, thelow-voltage power in the signal LVD may be routed through the switch 108to the signal LVB and out to the high-power loads 94.

If insufficient electrical power is received from the battery chargerplug 110, the electronic control unit 114 may command the converter 106into the down-conversion mode. The high-voltage battery 104 may providecurrent to the converter 106. The converter 106 may generate the signalLVC that is subsequently routed through the switch 108 to the auxiliarylow-voltage bus 90 as the signal LVB.

If the engine 72 is started while the electronic control unit 114 is inthe state 144, the electronic control unit 114 may command the switch tochange the connection for the signal LVB from the signal LVD back to thesignal LVC, if not already connected. The electronic control unit 114may subsequently transition (e.g., ICE ON) back to the state 142.

The state 146 may implement an auxiliary mode state. If the batterycharger plug 110 is unplugged and the engine 72 is off while in thestate 144, the electronic control unit 114 may transition (e.g.,UNPLUGGED) to the state 146. While in the auxiliary mode state 146, theelectronic control unit 114 may command the switch 108 to routelow-voltage power from the signal LVE to the signal LVB. The switch 108may route the power to the high-power loads 94 as the signal LVB.

If insufficient power is available from the auxiliary connector 124, andsince the engine 72 is not running while in the state 146, theelectronic control unit 114 may command the converter 106 into thedown-conversion mode, and command the switch 108 to connect the signalLVC to the signal LVB. The high-voltage energy stored in thehigh-voltage battery 104 may be discharged into the converter 106. Theconverter 106 may generate low-voltage power in the signal LVC.

If the battery charger plug 110 receives power while in the state 146,the electronic control unit 114 may transition (e.g., PLUGGED) back tothe state 144. Thereafter, the electronic control unit 114 may commandthe switch 108 to route power from the signal LVD to the signal LVB todrive the high-power loads 94.

If the engine 72 is started while in the state 146, the electroniccontrol unit 114 may transition (e.g., ICE ON) back to the state 142.The electronic control unit 114 may command the converter 106 into thedown-conversion mode and command the switch 108 to route the low-voltagepower in the signal LVC to the signal LVB to drive the high-power loads94.

The state 148 may implement a wall charger mode. Upon a transition(CHARGE CMD) to the state 148, the electronic control unit 114 maycommand the switch 108 to connect the signal LVD to the signal LVC inthe state 148. The electronic control unit 114 may also command theconverter 106 into the up-conversion mode. In the up-conversion mode,the converter 106 may charge the high-voltage battery 104 using thepower in the signal LVC as received from the battery charger plug 110.In some embodiments, the switch 108 may also be commanded to route powerfrom the signal LVD to the signal LVB to recharge the auxiliary systembackup battery 112. Once the high-voltage battery 104, and optionallythe auxiliary system backup battery 112, are sufficiently rechargedand/or the user chooses to end the recharging, the electronic controlunit 114 may return (NORMAL CMD) to the state 144 by issuing a set ofcommands to the switch 108 and the converter 106.

The state 150 may implement an auxiliary charge state. From the state146, the electronic control unit 114 may transition (CHARGE CMD) to thestate 150. In the state 150, the electronic control unit 114 may commandthe switch 108 to connect the signal LVE to the signal LVC. Theelectronic control unit 114 may also command the converter 106 into theup-conversion mode. In the up-conversion mode, the converter 106 maycharge the high-voltage battery 104 using the power in the signal LVCreceived through the auxiliary connector 124. In some embodiments, theswitch 108 may also be commanded to route power from the signal LVE tothe signal LVB to recharge the auxiliary system backup battery 112. Oncethe high-voltage battery 104, and optionally the auxiliary system backupbattery 112, are sufficiently recharged and/or the user chooses to endthe recharging, the electronic control unit 114 may return (NORMAL CMD)to the state 146 by issuing a set of commands to the switch 108 and theconverter 106.

If the battery charger plug 110 receives power while in the state 150,the electronic control unit 114 may transition (PLUGGED) back to thestate 148 and command the switch 108 to route power from the signal LVDto the signal LVB. If the battery charger plug 110 loses power while inthe state 148, the electronic control unit 114 may transition(UNPLUGGED) to the state 150 and command the switch to route power fromthe signal LVE to the signal LVB. While five states are illustrated inthe example implementation, other numbers of state and transitiontriggers may be implemented to meet the design criteria of a particularapplication.

The functions performed by the diagrams of FIGS. 1-3 may be implementedusing one or more of a conventional general purpose processor, digitalcomputer, microprocessor, microcontroller, RISC (reduced instruction setcomputer) processor, CISC (complex instruction set computer) processor,SIMD (single instruction multiple data) processor, signal processor,central processing unit (CPU), arithmetic logic unit (ALU), videodigital signal processor (VDSP) and/or similar computational machines,programmed according to the teachings of the specification, as will beapparent to those skilled in the relevant art(s). Appropriate software,firmware, coding, routines, instructions, opcodes, microcode, and/orprogram modules may readily be prepared by skilled programmers based onthe teachings of the disclosure, as will also be apparent to thoseskilled in the relevant art(s). The software is generally executed froma medium or several media by one or more of the processors of themachine implementation.

The invention may also be implemented by the preparation of ASICs(application specific integrated circuits), Platform ASICs, FPGAs (fieldprogrammable gate arrays), PLDs (programmable logic devices), CPLDs(complex programmable logic devices), sea-of-gates, RFICs (radiofrequency integrated circuits), ASSPs (application specific standardproducts), one or more monolithic integrated circuits, one or more chipsor die arranged as flip-chip modules and/or multi-chip modules or byinterconnecting an appropriate network of conventional componentcircuits, as is described herein, modifications of which will be readilyapparent to those skilled in the art(s).

The invention thus may also include a computer product which may be astorage medium or media and/or a transmission medium or media includinginstructions which may be used to program a machine to perform one ormore processes or methods in accordance with the invention. Execution ofinstructions contained in the computer product by the machine, alongwith operations of surrounding circuitry, may transform input data intoone or more files on the storage medium and/or one or more outputsignals representative of a physical object or substance, such as anaudio and/or visual depiction. The storage medium may include, but isnot limited to, any type of disk including floppy disk, hard drive,magnetic disk, optical disk, CD-ROM, DVD and magneto-optical disks andcircuits such as ROMs (read-only memories), RAMs (random accessmemories), EPROMs (erasable programmable ROMs), EEPROMs (electricallyerasable programmable ROMs), UVPROMs (ultra-violet erasable programmableROMs), Flash memory, magnetic cards, optical cards, and/or any type ofmedia suitable for storing electronic instructions.

The terms “may” and “generally” when used herein in conjunction with“is(are)” and verbs are meant to communicate the intention that thedescription is exemplary and believed to be broad enough to encompassboth the specific examples presented in the disclosure as well asalternative examples that could be derived based on the disclosure. Theterms “may” and “generally” as used herein should not be construed tonecessarily imply the desirability or possibility of omitting acorresponding element.

While the invention has been particularly shown and described withreference to embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made withoutdeparting from the scope of the invention.

The invention claimed is:
 1. An apparatus comprising: a first interfaceconfigured to receive a first low-voltage signal from a first power railof a vehicle; a first converter configured to generate a high-voltagesignal by up-converting said first low-voltage signal; a high-voltagebattery configured to store said high-voltage signal; a second converterconfigured to generate a second low-voltage signal by down-convertingsaid high-voltage signal; a second interface configured to present saidsecond low-voltage signal to a second power rail of said vehicle; aswitch configured to route said second low-voltage signal to said secondpower rail while said apparatus is in a first mode; and a charger plugconnected to said switch and configured to receive a third low-voltagesignal from a source external to said vehicle, wherein (i) said firstpower rail is electrically separated from said second power rail and(ii) said switch is configured to route said third low-voltage signal tosaid second power rail while said apparatus is in a second mode.
 2. Theapparatus according to claim 1, wherein said first low-voltage signal isgenerated from power derived from an internal combustion engine of saidvehicle.
 3. The apparatus according to claim 1, wherein said switch isfurther configured to disconnect said second low-voltage signal fromsaid second power rail while said apparatus is in said second mode. 4.The apparatus according to claim 1, further comprising a third interfaceconnected to said switch and configured to receive a fourth low-voltagesignal from an exterior power source, wherein said switch is furtherconfigured to route said fourth low-voltage signal to said second powerrail while said apparatus is in a third mode.
 5. The apparatus accordingto claim 4, wherein said switch is further configured to disconnect saidthird low-voltage signal from said second power rail while saidapparatus is in said third mode.
 6. The apparatus according to claim 1,further comprising a low-voltage battery connected to said second powerrail, wherein (i) said switch is a break-before-make switch whenchanging between modes and (ii) said low-voltage battery maintains poweron said second power rail while said switch breaks all connections whilechanging between modes.
 7. The apparatus according to claim 1, whereinsaid switch is further configured to route said third low-voltage signalfrom said charger plug to said second converter while said apparatus isin said second mode.
 8. The apparatus according to claim 7, wherein saidsecond converter is further configured to recharge said high-voltagebattery by up-converting said third low-voltage signal.
 9. The apparatusaccording to claim 1, further comprising an electronic control unitconfigured to control a mode of said apparatus in response to aplurality of commands received from a user interface device of saidvehicle.
 10. The apparatus according to claim 9, wherein said electroniccontrol unit is further configured to control said second converterbetween an up-conversion mode and a down-conversion mode.
 11. Theapparatus according to claim 9, wherein said electronic control unit isfurther configured to report a status of said switch to said userinterface device.
 12. The apparatus according to claim 1, wherein (i)said first power rail has a first voltage in a first range fromapproximately 10 volts to approximately 50 volts, (ii) said high-voltagebattery has a second voltage in a second range from approximately 200volts to approximately 600 volts, and (iii) said second power raildrives one or more loads up to 15,000 watts.
 13. A method for auxiliarypower distribution in a vehicle, comprising the steps of: receiving afirst low-voltage signal from a first power rail of said vehicle;generating a high-voltage signal by up-converting said first low-voltagesignal; storing said high-voltage signal; generating a secondlow-voltage signal by down-converting said high-voltage signal;presenting said second low-voltage signal to a second power rail of saidvehicle; routing said second low-voltage signal to said second powerrail while in a first mode; and receiving a third low-voltage signalfrom a source external to said vehicle, wherein (i) said first powerrail is electrically separated from said second power rail and (ii) saidthird low-voltage signal is configured to be routed to said second powerrail while in a second mode.
 14. An apparatus comprising: a firstinterface configured to receive a first low-voltage signal from a firstpower rail of a vehicle; a first converter configured to generate ahigh-voltage signal by up-converting said first low-voltage signal; ahigh-voltage battery configured to store said high-voltage signal; asecond converter configured to generate a second low-voltage signal bydown-converting said high-voltage signal; a second interface configuredto present said second low-voltage signal to a second power rail of saidvehicle; a switch configured to route said second low-voltage signal tosaid second power rail while said apparatus is in a first mode; and anelectronic control unit configured to control a mode of said apparatusin response to a plurality of commands received from a user interfacedevice of said vehicle, wherein (i) said first power rail iselectrically separated from said second power rail and (ii) saidelectronic control unit is further configured to control said secondconverter between an up-conversion mode and a down-conversion mode.